The present invention relates generally to breathing apparatus and, more particularly, to a universal interface for a breathing apparatus which is specifically adapted to provide continuous positive airway pressure (CPAP) when the interface is used with a standard ventilator and which further is constructed with unique geometries to increase stagnation pressure (i.e., patient pressure) with minimal supply pressure as well as reduced exhalation resistance in order to improve the work of breathing.
The use of breathing apparatus upon respiratory-impaired patients is well known. Generally, such apparatuses assist in patient breathing by allowing proper exchange of inhaled and exhaled gas while providing pressurized gasses to a patient's lungs so as to prevent lung collapse. In this manner, conventional breathing apparatus operate to allow spontaneous breathing of the patient while sustaining the application of continuous positive airway pressure (CPAP) to the patient's lungs.
The types of breathing apparatus mentioned above have proven to be effective in patients whose ability to breathe is impaired. For example, babies born with lung disease or other complications may require ventilatory support using CPAP therapy. Ideally, CPAP therapy delivers a constant stable pressure to the mouth, nose or via a tracheal tube inserted in the infant. Although the use of such apparatus has generally proven to be suitable for their intended purposes, such prior art breathing apparatus possess certain design deficiencies which detract from their overall effectiveness and desirability.
For example, flow generators are a type of device that can be used with the above-mentioned breathing apparatus in providing CPAP therapy treatment. As was earlier mentioned, in CPAP ventilation, high pressure gas must be supplied to the airways of the patient on a constant basis. In this regard, a flow generator may be used with a conventional ventilator. Unfortunately, conventional ventilators typically operate at a lower pressure than the pressure required for CPAP therapy treatment.
Therefore, one design deficiency characterizing prior art flow generators is that such flow generators require the use of excessive supply pressure in order to create sufficient pressure at the patient. More particularly, it is understood that such prior art flow generators require up to 205 centimeters of H2O of supply pressure in order to create up to about 10 to 15 cm of H2O at the patient. However, federal standards limit the amount of supply pressure that can be utilized in CPAP therapy for certain patients. For example, in neonates, the recommended maximum supply pressure is limited to 120 centimeters (cm) of H2O. Furthermore, prior art flow generators require high supply pressure (e.g., 205 cm of H2O) in order to achieve a desired flow rate of 12 liters/minute (LPM) to the patient.
As may be appreciated, dangerously high supply pressures as required in prior art flow generators may subject the patient to the risk of injury. For example, high pressures within the patient airway can cause damage to lungs as well as other organs. In addition, exposure to high pressure in the patient airway may result in other respiratory complications. Another deficiency associated with prior art flow generators is that the requirement for excessive supply pressures requires a concomitant increased amount of power in order to generate the desired amount of patient pressure. In this regard, prior art flow generators are relatively inefficient and unsafe when used in CPAP therapy.
As can be seen, there exists a need in the art for a universal interface that may be adapted for providing continuous positive airway pressure (CPAP) with reduced supply gas pressure in order to minimize the risks posed by excessive pressures in the patient's airway. Furthermore, there exists a need in the art for a universal interface for CPAP ventilation that is configured to operate with a standard ventilator at a supply pressure of no greater than about 120 cm of H2O in order to provide up to about 15 cm of H2O at the patient, depending on the supply pressure.
In addition, there exists a need in the art for a universal interface for CPAP therapy that is configured to provide a flow rate of up to about 12 liters/minute to the patient while the supply pressure is limited to 120 cm of H2O. Also, there exists a need in the art for a universal interface for CPAP therapy that is of simple and thereby inexpensive design and which is specifically configured to sustain a positive airway pressure at the patient with minimal supply pressure while reducing exhalation resistance in order to improve the work of breathing.